Breathing movements in the frog Rana pipiens. II. The power output and efficiency of breathing

1975 ◽  
Vol 53 (3) ◽  
pp. 345-353 ◽  
Author(s):  
N. H. West ◽  
D. R. Jones
Keyword(s):  
Body Weight ◽  
Power Output ◽  
Rana Pipiens ◽  
Buccal Cavity ◽  
Respiratory Muscles ◽  
Lung Ventilation ◽  
Pressure Change ◽  
Mechanical Efficiency ◽  
Lung Inflation ◽  
Anticlockwise Direction

The work done by the buccal cavity during buccal and lung ventilation cycles has been estimated from measurement of the area enclosed by pressure–volume loops for each cycle. The loops cycled in an anticlockwise direction with respect to time during buccal cycles. On the other hand, pressure–volume loops from the lungs cycled clockwise, showing that work was being done on the lungs by the buccal pump. Inflation and deflation of the buccal cavity from a syringe, in curarized frogs, gave a clockwise loop enclosing about 5.5–6.5% of the area enclosed by a naturally generated loop of the same pressure and volume. However, inflation and deflation of the lungs gave a loop which enclosed an area virtually identical with that obtained from a normally generated sequence of lung inflation and deflation. The power output of the buccal pump was directly proportional to body weight, the major determinant of the former being the larger buccal volume rather than pressure change as body weight increased. The mechanical efficiency of the buccal pump varied from 0.4% to 16.2%, efficiency increasing with increased power output over most of the physiological range. Mean efficiency of all buccal movements was calculated to be 8% and, at this value of efficiency, oxygen consumption of the respiratory muscles was 0.89 ml O2 100 g−1 min−1. In Rana pipiens at rest the oxygen cost of breathing appears to be about 5% of the total resting metabolism.

Breathing movements in the frog Rana pipiens. I. The mechanical events associated with lung and buccal ventilation

1975 ◽  
Vol 53 (3) ◽  
pp. 332-344 ◽  
Author(s):  
N. H. West ◽  
D. R. Jones
Keyword(s):  
Rana Pipiens ◽  
Buccal Cavity ◽  
Lung Ventilation ◽  
Cavity Pressure ◽  
Normal Pattern ◽  
Large Pressure ◽  
Dilator Muscle ◽  
Recovery Stroke ◽  
Two Phases ◽  
Low Pressures

The normal pattern of breathing movements in Rana pipiens has been studied by recording pressure and volume changes in the buccal cavity and lungs, and electromyograms from the muscles involved in this activity. Two types of breathing movement were obtained, one concerned with ventilation of the buccal cavity (buccal cycles) and the other with lung ventilation (lung cycles). Only in the latter type of movement were the nares and glottis actively involved. During buccal cycles the nares remained open and the glottis closed, so although excursions of the buccal floor were some two-thirds of the magnitude of those occurring during lung cycles, only low pressures were generated. The onset of a lung cycle was signalled by activity in the laryngeal dilator muscle. When the glottis opened, lung pressure and volume decreased, and buccal cavity pressure and volume increased. After closure of the nares, the buccal floor was rapidly elevated by the activity of the breathing muscles and air was forced into the lungs from the buccal cavity. At peak pressure in the lungs and buccal cavity the glottis closed and nares opened. The recovery stroke of the buccal pump was passive. No evidence was found for large pressure differentials between the buccal cavity and lungs when the glottis was open, and air-flow recordings at the external nares showed two phases of flow during each buccal cycle and four phases with each lung ventilation cycle.

The initiation of diving apnoea in the frog, Rana pipiens

1976 ◽  
Vol 64 (1) ◽  
pp. 25-38
Author(s):  
N. H. West ◽  
D. R. Jones
Keyword(s):  
Electrical Stimulation ◽  
Water Level ◽  
Rana Pipiens ◽  
Buccal Cavity ◽  
Respiratory Muscles ◽  
Normal Pattern ◽  
Water Head ◽  
Response To Water ◽  
Water Meniscus ◽  
Stimulation Of

1. Diving apnoea in Rana pipiens was initiated by submerging the external nares. As the water level was raised above the frog, both buccal and lung pressure increased by an amount corresponding to the water head. During submergence the external nares remained closed, although the apnoeic period was punctuated by ventilation movements which moved gas between the lungs and buccal cavity. 2. Bilateral section of the ophthalmic nerves did not alter the normal pattern of ventilation in air, although it often resulted in the intake of water into the buccal cavity on submergence. Introduction of water into the buccal cavity, either naturally as in denervates or by injection through a catheter in intact frogs, triggered sustained electromyographical activity in some respiratory muscles. 3. Electroneurograms recorded from the cut peripheral end of an ophthalmic nerve showed that receptors in the external narial region were stimulated by movement of a water meniscus across them. Activity could also be recorded in the ophthalmic nerve in response to water flow past the submerged nares. Punctate stimulation of the narial region confirmed that these receptors were mechanosensitive. 4. Bilateral electrical stimulation of the central ends of cut ophthalmic nerves in lightly anaesthetized frogs caused apnoea with a latency of less than 200 ms. The external nares remained closed throughout the period of stimulation although buccal pressure events, resembling underwater ventilation movements, occurred when stimulation was prolonged.

Ventilatory Mechanisms of the Amphibian, Xenopus Laevis; The Role of the Buccal Force Pump

1979 ◽  
Vol 80 (1) ◽  
pp. 251-269 ◽  
Author(s):  
S. S. BRETT ◽  
G. SHELTON
Keyword(s):  
Xenopus Laevis ◽  
Buccal Cavity ◽  
Respiratory Muscles ◽  
Lung Ventilation ◽  
Cavity Volume ◽  
Lung Volumes ◽  
Expired Air

1. Lung pressures, buccal pressures, lung volumes, and EMGs from respiratory muscles were measured in unrestrained Xenopus laevis to analyse their roles in the lung ventilation cycle. 2. Lung pressure was always maintained above atmospheric levels and a buccal pumping mechanism was used to fill the lungs in Xenopus, as in other Amphibia. 3. Xenopus, unlike other amphibians, does not ventilate the buccal cavity between lung ventilations. 4. Expiration of gases from the buccal cavity is aided by muscles which decrease buccal cavity volume. Other anurans increase buccal cavity volume during expiration. 5. The buccal phase of inspiration occurs after expired air has passed from the lung and buccal cavity, in comparison to the ranids and bufonids which inspire fresh air into the buccal cavity before expiration.

Effects of lung volume and O2 and CO2 content on cutaneous gas exchange in frogs

1986 ◽  
Vol 251 (5) ◽  
pp. R941-R946
Author(s):  
G. M. Malvin ◽  
M. P. Hlastala
Keyword(s):  
Gas Exchange ◽  
Mass Spectrometer ◽  
Lung Volume ◽  
Rana Pipiens ◽  
Lung Ventilation ◽  
Small Sample ◽  
Cholinergic Nerves ◽  
Lung Inflation ◽  
Sample Chamber ◽  
Cutaneous Respiration

The effects of lung O2 and CO2 content and volume on cutaneous gas exchange and perfusion were investigated in the frog, Rana pipiens. (Ha)-anesthetized frogs were equilibrated with 9.5% Freon-22 (Fr, chlorodifluoromethane) and 1.1% Ha. Cutaneous elimination of Fr, Ha, and CO2 into a small sample chamber on the abdomen was measured with a mass spectrometer. Introducing an air mixture into the lung decreased cutaneous Fr, Ha, and CO2 elimination. Lung inflation with an O2 mixture decreased cutaneous gas elimination more than with the air mixture. Inflation with a N2 mixture had no effect. The response to lung inflation with the air mixture was not affected by adding 4.8% CO2 to the air mixture or by atropine. Voluntary lung ventilation decreased CO2 and Fr elimination. The results indicate that intrapulmonary O2 is a factor regulating skin breathing. If a change in lung volume is also a factor, it requires a concomitant change in lung O2. Intrapulmonary CO2 and cholinergic nerves are not involved in cutaneous respiration across the abdomen.

Breathing in Rana Pipiens: the Mechanism of Ventilation

1990 ◽  
Vol 154 (1) ◽  
pp. 537-556 ◽  
Author(s):  
TIMOTHY ZOLTAN VITALIS ◽  
GRAHAM SHELTON
Keyword(s):  
Lung Volume ◽  
Rana Pipiens ◽  
Buccal Cavity ◽  
Air Flow ◽  
Lung Ventilation ◽  
Jet Stream ◽  
Pulmonary Pressure ◽  
Simultaneous Measurements ◽  
Low Amplitude ◽  
Ventilation Of The Lungs

The mechanism and pattern of ventilation in unrestrained Rana pipiens were investigated by simultaneous measurements of pulmonary pressure, buccal pressure and air flow at the nostrils. The buccal cavity was ventilated continuously at a rate of 90±3.2oscillations min−1 by low-amplitude pressure swings above and below atmospheric. The lungs were ventilated intermittently by the buccal pump at a rate of 6.3±0.8breathsmin−1. Expiration of gas from the nostrils occurred on two occasions during a lung ventilation. Ventilation of the lungs was achieved by precise timing of two valves, the nostrils and glottis. The timing of the valves determined the volume of expiratory flow on these two occasions and its relationship to inspiratory flow. Thus, the breathing movements could cause inflation, deflation, or no change in the lung volume. Periodically the lung was inflated by a sequence of successive breaths. During inflations the nostrils closed simultaneously with glottal opening and almost no gas was expired during the first expiratory phase. This caused a complete mixing of buccal contents and pulmonary gas and this mixture was pumped back into the lung. Deflations were characterized by a delay in nostril closing that resulted in a large outflow of gas from the lung and buccal cavity during the first phase of expiration. More gas left the system than was pumped into the lungs. The results suggest that coherent air flow from glottis to nostrils, as required by the ‘jet stream’ hypothesis of Gans et al. (1969), is not likely to occur.

A Systematic Review of Submaximal Cycle Tests to Predict, Monitor, and Optimize Cycling Performance

2016 ◽  
Vol 11 (6) ◽  
pp. 707-714 ◽  
Author(s):  
Benoit Capostagno ◽  
Michael I. Lambert ◽  
Robert P. Lamberts
Keyword(s):  
Heart Rate ◽  
Power Output ◽  
Perceived Exertion ◽  
Heart Rate Recovery ◽  
Mechanical Efficiency ◽  
Cycling Performance ◽  
Rating Of Perceived Exertion ◽  
Time To Exhaustion ◽  
Gross Mechanical Efficiency ◽  
Multiple Variables

Finding the optimal balance between high training loads and recovery is a constant challenge for cyclists and their coaches. Monitoring improvements in performance and levels of fatigue is recommended to correctly adjust training to ensure optimal adaptation. However, many performance tests require a maximal or exhaustive effort, which reduces their real-world application. The purpose of this review was to investigate the development and use of submaximal cycling tests that can be used to predict and monitor cycling performance and training status. Twelve studies met the inclusion criteria, and 3 separate submaximal cycling tests were identified from within those 12. Submaximal variables including gross mechanical efficiency, oxygen uptake (VO2), heart rate, lactate, predicted time to exhaustion (pTE), rating of perceived exertion (RPE), power output, and heart-rate recovery (HRR) were the components of the 3 tests. pTE, submaximal power output, RPE, and HRR appear to have the most value for monitoring improvements in performance and indicate a state of fatigue. This literature review shows that several submaximal cycle tests have been developed over the last decade with the aim to predict, monitor, and optimize cycling performance. To be able to conduct a submaximal test on a regular basis, the test needs to be short in duration and as noninvasive as possible. In addition, a test should capture multiple variables and use multivariate analyses to interpret the submaximal outcomes correctly and alter training prescription if needed.

scholarly journals Assessment of the influence of lung inflation state on the quantitative parameters derived from hyperpolarized gas lung ventilation MRI in healthy volunteers

2019 ◽  
Vol 126 (1) ◽  
pp. 183-192 ◽  
Author(s):  
Paul J. C. Hughes ◽  
Laurie Smith ◽  
Ho-Fung Chan ◽  
Bilal A. Tahir ◽  
Graham Norquay ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Lung Volume ◽  
Lung Ventilation ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Longitudinal Measurements ◽  
Anatomical Images ◽  
Lower Lung ◽  
Ventilation Heterogeneity ◽  
Residual Capacity

In this study, the effect of lung volume on quantitative measures of lung ventilation was investigated using MRI with hyperpolarized 3He and 129Xe. Six volunteers were imaged with hyperpolarized 3He at five different lung volumes [residual volume (RV), RV + 1 liter (1L), functional residual capacity (FRC), FRC + 1L, and total lung capacity (TLC)], and three were also imaged with hyperpolarized 129Xe. Imaging at each of the lung volumes was repeated twice on the same day with corresponding 1H lung anatomical images. Percent lung ventilated volume (%VV) and variation of signal intensity [heterogeneity score (Hscore)] were evaluated. Increased ventilation heterogeneity, quantified by reduced %VV and increased Hscore, was observed at lower lung volumes with the least ventilation heterogeneity observed at TLC. For 3He MRI data, the coefficient of variation of %VV was <1.5% and <5.5% for Hscore at all lung volumes, while for 129Xe data the values were 4 and 10%, respectively. Generally, %VV generated from 129Xe images was lower than that seen from 3He images. The good repeatability of 3He %VV found here supports prior publications showing that percent lung-ventilated volume is a robust method for assessing global lung ventilation. The greater ventilation heterogeneity observed at lower lung volumes indicates that there may be partial airway closure in healthy lungs and that lung volume should be carefully considered for reliable longitudinal measurements of %VV and Hscore. The results suggest that imaging patients at different lung volumes may help to elucidate obstructive disease pathophysiology and progression. NEW & NOTEWORTHY We present repeatability data of quantitative metrics of lung function derived from hyperpolarized helium-3, xenon-129, and proton anatomical images acquired at five lung volumes in volunteers. Increased regional ventilation heterogeneity at lower lung inflation levels was observed in the lungs of healthy volunteers.

scholarly journals Total power output generated during dynamic knee extensor exercise at different contraction frequencies

2000 ◽  
Vol 89 (5) ◽  
pp. 1912-1918 ◽  
Author(s):  
Richard A. Ferguson ◽  
Per Aagaard ◽  
Derek Ball ◽  
Anthony J. Sargeant ◽  
Jens Bangsbo
Keyword(s):  
Power Output ◽  
Accurate Determination ◽  
Knee Extensor ◽  
Mechanical Efficiency ◽  
Muscle Group ◽  
Total Power ◽  
Mechanical Power Output ◽  
External Power ◽  
Power Outputs ◽  
Total Power Output

A novel approach has been developed for the quantification of total mechanical power output produced by an isolated, well-defined muscle group during dynamic exercise in humans at different contraction frequencies. The calculation of total power output comprises the external power delivered to the ergometer (i.e., the external power output setting of the ergometer) and the “internal” power generated to overcome inertial and gravitational forces related to movement of the lower limb. Total power output was determined at contraction frequencies of 60 and 100 rpm. At 60 rpm, the internal power was 18 ± 1 W (range: 16–19 W) at external power outputs that ranged between 0 and 50 W. This was less ( P < 0.05) than the internal power of 33 ± 2 W (27–38 W) at 100 rpm at 0–50 W. Moreover, at 100 rpm, internal power was lower ( P < 0.05) at the higher external power outputs. Pulmonary oxygen uptake was observed to be greater ( P< 0.05) at 100 than at 60 rpm at comparable total power outputs, suggesting that mechanical efficiency is lower at 100 rpm. Thus a method was developed that allowed accurate determination of the total power output during exercise generated by an isolated muscle group at different contraction frequencies.

Change in extra-alveolar perimicrovascular pressure with lung inflation

1984 ◽  
Vol 57 (3) ◽  
pp. 772-776 ◽  
Author(s):  
A. C. Jasper ◽  
H. S. Goldberg
Keyword(s):  
Hydrostatic Pressure ◽  
Volume Change ◽  
Transpulmonary Pressure ◽  
Pressure Change ◽  
Dry Mass ◽  
Interstitial Pressure ◽  
Autologous Plasma ◽  
Lung Inflation ◽  
Pulmonary Arterial ◽  
Over Time

In eight isolated dog lobes, we examined the change in extra-alveolar perimicrovascular hydrostatic pressure (Pis) due to lung inflation. The vasculature was filled with autologous plasma. Pulmonary arterial and venous lines were connected to a common plasma reservoir. Perimicrovascular volume change (delta Vis), compliance (Cis), and the microvascular filtration coefficient (Kf) were derived from the change in lobe mass over time following a step increase in vascular pressure (Piv). Initially, transpulmonary pressure (PL) was 5 cmH2O and Piv = 0 cmH2O. At constant Piv, two sequential 5-cmH2O increases in PL increased Vis; division of delta Vis by Cis yielded the change in Pis attributable to lung inflation. Cis was 0.035 +/- 0.018 g X cmH2O–1 X g dry mass-1 (mean +/- SD) at PL = 15 cmH2O. Kf was 0.019 +/- 0.023 g X min-1 X cmH2O–1 X g dry mass-1. With inflation from PL = 5 to PL = 10 cmH2O, Pis = -2.15 +/- 1.76 cmH2O; from PL = 10 to PL = 15 cmH2O, Pis = -2.25 +/- 1.50 cmH2O. This perimicrovascular pressure change is very close to the perihilar interstitial pressure change reported by others. Such near equality suggests that the stress of lung inflation is very uniformly applied to the interstitial continuum.

Standardized Unloading of Respiratory Muscles during Neurally Adjusted Ventilatory Assist

2018 ◽  
Vol 129 (4) ◽  
pp. 769-777 ◽  
Author(s):  
Francesca Campoccia Jalde ◽  
Fredrik Jalde ◽  
Mats K. E. B. Wallin ◽  
Fernando Suarez-Sipmann ◽  
Peter J. Radell ◽  
...  
Keyword(s):  
Pressure Support ◽  
Respiratory Muscles ◽  
Lung Ventilation ◽  
Interquartile Range ◽  
Secondary Outcome ◽  
Neurally Adjusted Ventilatory Assist ◽  
Impedance Tomography ◽  
Respiratory Parameters ◽  
Ventilatory Parameters ◽  
Ventilatory Assist

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Currently, there is no standardized method to set the support level in neurally adjusted ventilatory assist (NAVA). The primary aim was to explore the feasibility of titrating NAVA to specific diaphragm unloading targets, based on the neuroventilatory efficiency (NVE) index. The secondary outcome was to investigate the effect of reduced diaphragm unloading on distribution of lung ventilation. Methods This is a randomized crossover study between pressure support and NAVA at different diaphragm unloading at a single neurointensive care unit. Ten adult patients who had started weaning from mechanical ventilation completed the study. Two unloading targets were used: 40 and 60%. The NVE index was used to guide the titration of the assist in NAVA. Electrical impedance tomography data, blood-gas samples, and ventilatory parameters were collected. Results The median unloading was 43% (interquartile range 32, 60) for 40% unloading target and 60% (interquartile range 47, 69) for 60% unloading target. NAVA with 40% unloading led to more dorsal ventilation (center of ventilation at 55% [51, 56]) compared with pressure support (52% [49, 56]; P = 0.019). No differences were found in oxygenation, CO2, and respiratory parameters. The electrical activity of the diaphragm was higher during NAVA with 40% unloading than in pressure support. Conclusions In this pilot study, NAVA could be titrated to different diaphragm unloading levels based on the NVE index. Less unloading was associated with greater diaphragm activity and improved ventilation of the dependent lung regions.

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